Cupola type furnace



Jan. 3, 1950 E. s. RENSHAW ET AL. 7 2,493,642

GUPOLA TYPE FURNACE Filed March 26, 1945 [dim d Jam/nag f 60.76011 5/0 0 film-j jar-9000 IN V EN TOR:

BY ZZZ.

QF-fi a Patented Jan. 3, 1950 CUPOLA TYPE FURNACE Edward Summers Renshaw, Upminster, and Sidney James Sal-good, Ilford, England, assignors to Ford Motor Company, Dearborn, Mich.

Application March 26, 1945, Serial No. 584,774 In Great Britain June 6, 1944 2 Claims.

It is customary practice to line the hearth and 'vertical stack of the furnace with acid or basic refractories and the length of the operating time 'of the furnace depends mainly on the extent of fusion and erosion of the refractory materials employed. Such fusion and erosion are most severe in the zone immediately above the tuyres in which maximum combustion of the coke fuel occurs and the face of the refractory lining is in consequence exposed to a temperature at or near the fusion point of the refractory. Moreover, slag erosion becomes severe in this region owing to "the refractory being at a temperature near its softening point.

In view of the foregoing it is found that with cupola type furnaces as hitherto constructed the operative period of the furnace is very short with the result that the furnace must be continually shut down to enable the necessary repairs to be effected.

The object of the present invention is to prolong the operating time of the furnace and so increase its output while at the same time reducing the labor and material required for maintenance. A

further advantage of the invention is that it per- 1 mits of a more positive control ofslag composition owing to the amount of refractory that is absorbed by the slag being so small as to be practically negligible.

The invention consists in a cupola type furnace in which the wall in the neighborhood of the tuyres is lined with a cast steel or other metal lining adapted to be cooled by the application of cooling medium thereto.

The invention also consists in a cupola type furnace in which the combustion and melting zone between the hearth and the stack is of conical form tapering inwards towards the stack, the base of such zone immediately above the tuyeres being formed of or lined with a cast steel or other hollow structure, the interior of which is supplied with a cooling medium.

The accompanying drawing illustrates in part sectional elevation in one convenient form of cupola type furnace'constructed in accordance with the invention.

In carrying our invention into effect in one convenient manner, we form our cupola type furnace with a conventional stack I (only a portion of which is shown extending about as far as the usual charging floor level) and hearth 2, but in place of forming the combustion and melting zone portion 3 as a vertical continuation of the stack as is usual, we make this zone of conical form as shown with its base supported by a series of steel gussets l or other supports arranged at convenient intervals beneath the said base. The distance between the tuyres 5, and the point where the conical section 3 meets the stack I is determined by the coke bed height with which it is normal to operate, but by way of example'it may be noted that in one cupola of this type, the normal coke bed height may be 46 inches above the tuyres and the cone height above the tuyeres would be 42 inches. The portion of the furnace wall between the base of the refractory cone portion 3 and the inner edge of the tuyeres is lined with a series of cast steel or other metal segments 6, there being conveniently one of said segments for each tuyere, and the base of each such segment forming the upper portion of the tuyre. Here again, however, it will be understood that this arrangement is purely by way of example and that any other suitable arrangement may be adopted. The contour of each segment approximates to the line of erosion'in the area of the furnace in which it is located and each segment is made hollow so that water or other cooling medium may be admitted thereto. In the particular construction illustrated the cooling medium is supplied to the segments through the cooling pipes I from a supply main, so that each segment has a separate feed and each also has a separate outlet 8, all the outlets 8 leading to a suitable waste means. Moreover, baflle plates are preferably fltted internally of the cooler segments to ensure satisfactory circulation of the cooling medium and the latter may be recirculated by a suitable return system if desired. The shape of the cooling segments may be varied to suit individual requirements.

The tuyeres 5 are connected through ducts 9 with the wind box In to supply the air required for operation. As is customary, the hearth is hinged at II to permit dumping of the cupola residue. A sand bottom may be laid on the hearth and the metal withdrawn through the usual iron notch I 2, while a cinder notch permits withdrawal of the slag. The cupola itself is made with the steel shell or casing I3 and the usual refractory lining 14, except in the immediate vicinity of the tuyres where they are replaced by the segments 6 which are filleted in place by refractory matetrial Hi.

It will be seen that the refractory face which is subject to maximum heating and erosion has been removed to a position remote from the tuyere inlet in order to ensure that the refractory will be subject to temperatures below the softening point of the refractory. Moreover, the angle of inclina.

tion of the refractory face is such as to prevent the slag and molten metal formed during melting from flowing over the refractory face itself and attack from these sources is therefore negligible. Preferably, the minimum diameter of the section immediately above the tuyeres is greater than the diameter atthetopof the conical portion 3, thus preventing aany direct flowotmetalifrom impinging on the surface of the coolers.

As a result of the foregoing improvementayit; has been found that the operating periodlofthe.

refractory is at least 15 times as long 'as'that "obtainable with furnaces hitherto:-.constrncted :with ,1 the result that not only viazsthere ,considerablen economy in material and labor requiredifonmainsl tenance, but also greater tonnagescan be handled-U without the necessity for shutdown repairs, ,Jands.

furthermore, the negligible amount of refractory I absorbed by the slag enables a more positiye control of slag composition1to be obtained.

In basic lined,- as -,distinct fromuacidcrlined -cupo1as, the advantages are perhaps: more evident Vin-that basic, materials have a higher initialcost and :basicpatching materials arev limited in variety Moreover, whenoperating with wbasic Jinings, control ,of sl-ag compositionbecomesmore important in that a greater degree -of-.-*desulphur- V .lization-and dephosphorization is possible'withra \controlled s1ag. Inaddition, it nowbecomes possible to, line the. aconicalyportion with 1 :acidurefractory, the cooling segmentsacting-es. a neutral 7 :par tingl layen;

lnrpracticeethe coolingsegmentsmaybe-coated with-a thinlayerof refractory not exceeding 1" in-thickness oralternatively.;they maya berpainted with a coating-pf refractory was-h.

It will be, understood, however that the invention extends broadly ato-cupola type-furnaces--in which the wall in thenei-ghborhoodof thetuyeres formed of, or lined with, ,-a cast; steel another metal structure adapted to be supplied zwithlcooling ,medium -and is therefore :not to ba-lim-itedto the foregoing details,ofrconstructionrwhich are 7 given purely by way biz-example to indicateqthe nature of the invention andnot-to limit its scop 7 Having now. particularly ;.described :.and;ascertained the mature of our said invention-:andtin whatlmanner the same is-to -,be eperformed we ,declare that whatwe claim is:

-1. YA. cupola comprising; asstack,v .tu-yres, ,a

crucible, :and ea hinged 'hearth, said stack; being r 4 approximately cylindrical and resting upon a supporting structure having the shape of a truncated cone and sloping inwardly towards said stack, the top of said tuyeres being formed by 5 series of hollow metallic cooling segments which are surrounded by the base of said supporting structure-,- said liollowsmetalliccooling segments having inner surfacesawhichpslcipe inwardly towards the crucible and being arranged in the pmaform of a circle the least diameter of which is greater than the diameter of the stack, that por- *tionof thelining of the cupola immediately above the hollowmetallimcooling segments being acidic in::character*and:the lining below the hollow r1 5 emetallicrcooling segments being basic in character .whereby .the hollow metallic cooling segments'act'as a neutral parting layer.

2.'A cupola the lining of which is partially aoidimand partially basic, said acidic lining being separated from said basic lining by a hollow metallic-l memberswadapted sto. receive :i-ntemally cooling media-and which acts:as=;a neutral parting layer between the acidic lliningiandtheebasictlining whereby undesirable whemical ureactioni be- ;tween the-aeidic ,and'basic lining isuprevented, said hollow *metallidmember being located-immediately above the ituyeresbfsthe cupolan snowman ,SUMMEBSlRENSHAVS/fl SIDNEY JAMESLSARGOODM REFERENCES ICITED".

The following g'references sane c'of; 'recordtfinsthe file of this patent:

35 UNITED "STATES PATENTS Number Name Date i 57,969 Reese Sept.:l 1, 186.6 228,852 Y Armstrong etfal. June 15;:1880 ,40 320,586 Probert Junei 23nl8il5 432,280 Nenninger, =July;l5,;:l890 1,225,232 Fischer ,'May 8;; 1917 1,629,045 Parkerr c :May 17,1927 1,948,696 Brassert. et al. 0---- Feb;;27;;-1-9.3.4 5 2,283,163 --Brass.ert et a1;; .;May 193194 2 =2,-3.45 ,502= '-Reece W... n-.Mar-.,-28;:,1944

' FQREIGN=- PATENTS- I Number Country Date :1 59 853s GreatBritain s'..... ..Sept.25,:1863 

